Document the current behavior of the modifier (which inserts the
replies into the DOM tree), so that we can more easily see the effect
of changes in I2a70db01e9a8916c5636bc59ea8490166966d5ec.
Basically, add a reply to every comment, and dump the resulting HTML,
comparing it to previously generated expected HTML (which can be
checked visually). Have a look at the new HTML files.
Notably, the very first section in the "pl" example demonstrates a
case of wrong reply location due to list gap :) (T242822).
Change-Id: I4aed0f0b112f53d98e3fe1da4d40db8687c7e537